Recording and reproducing an MPEG information signal on/from a record carrier

ABSTRACT

During recording of an MPEG information signal on a record carrier (40), transport packets (P k ) are stored in signal blocks in a track (1) on the record carrier (40). x transport packets of the MPEG information signal are stored in the second block sections (SB) of y signal blocks, where x and y are integers, x≧1 and y&gt;1, more specifically, y&gt;x. Further, third block sections (TB) are present in one or more of the second block sections in the y signal blocks of a group for storing additional information, which additional information relates to the specific application of recording and reproducing the MPEG information signal on/from the record carrier.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a recording arrangement for recording aninformation signal in tracks on a record carrier, the recordingarrangement comprising

an input terminal for receiving the information signal,

channel encoding means for channel encoding the information signal so asto obtain a channel signal suitable for recording in a track on saidrecord carrier,

writing means for writing the channel signal in the track, the channelsignal comprising subsequent signal blocks, each signal block comprisinga first block section which comprises a synchronisation signal and asecond block section which comprises a number of channel bytes, to arecord carrier obtained with the recording arrangement, and to areproducing arrangement for reproducing the video signal from the recordcarrier.

A recording arrangement as given in the opening paragraph is known fromEP-A492.704, document (1) in the list of references that can be found atthe end of this application.

2. Description of the Related Art

The known arrangement is a recording arrangement of the helical scantype and records an information signal comprising a digital audio signaland a digital video signal in audio signal recording sectors and videosignal recording sectors respectively in subsequent tracks, where, whenrecording a track, the video signal recording sector in a track comesfirst and is followed by the audio signal recording sector. The order inwhich the sectors occur in a track can however also be in the reverseorder. Further, other sectors may be included in a track, such as aclock run-in area located at the beginning of a track, so as to enable alocking-in of the internal system clock on the signals read from thetrack, and preamble and postamble areas that are located between thevarious sectors and function as an edit gap. Reference is made in thisrespect to the earlier filed European patent applications No.93.202.950,reference (2) in the list of references and no. 93.201.263, reference(3) in the list of documents.

The prior art documents relate to proposals for the realisation of a newdigital video cassette (DVC) recorder standard, which enables therecording and reproduction of digital video and digital audio on/from alongitudinal magnetic record carrier. This new digital video recorderstandard will lead to new digital videorecorders/reproducers of theso-called DVC type.

SUMMARY OF THE INVENTION

The invention aims at providing a recording arrangement which is capableof recording other type of information signals in the known tape formatas defined in the preamble. The recording arrangement in accordance withthe invention is characterized in that the information signal is an MPEGinformation signal in accordance with an MPEG format, the MPEGinformation signal comprising subsequent transport packets, that thechannel encoding means are adapted to store each time informationincluded in x transport packets of the MPEG information signal in thesecond block sections of a group of y signal blocks of the channelsignal, that the second block section of at least the first signal blockof the group of y signal blocks comprise a third block section forstoring identification information identifying the signal block as beingthe first signal block of the group of y signal blocks, and that x and yare integers such that x≧1 and y>1.

More specifically, the recording arrangement in accordance with theopening paragraph is characterized in that the information signal is anMPEG information signal in accordance with an MPEG format, the MPEGinformation signal comprising subsequent transport packets, that thechannel encoding means are adapted to store each time informationincluded in x transport packets of the MPEG information signal in thesecond block sections of a group of y signal blocks of the channelsignal, that the second block sections of the signal blocks comprise athird block section for storing sequence number information relating toa sequence number of the signal blocks, and that x and y are integerssuch that x≧1 and y>1.

The invention is based on the following recognition. The draft GrandAlliance HDTV System Specification dated Feb. 22, 1994, document (4) inthe list of references, more specifically the chapters V and VI of thisspecification, comprises a description of a transport system fortransmitting an MPEG information signal, which includes a datacompressed digital video signal and a corresponding data compresseddigital audio signal, for broadcasting purposes or for transmission viaa cable network. The MPEG information signal is in the form of transportpackets having either an equal length or a variable length in time. Inboth cases however, a transport packet comprises 188 bytes ofinformation, the first byte being a synchronization byte.

A transmission such an MPEG information signal in the form of arecording on and a reproduction from a record carrier, such as amagnetic record career, require special measures to be taken in order torealize such kind of transmission via the known tape format. Morespecifically, the invention relates to storing the transport packets inthe signal blocks of the known tape format.

Generally, it can be said that, when storing the information included ina number of x transport packets of the MPEG information signal in anumber of y signal blocks, some unoccupied space remains available inthe y signal blocks for the storage of additional information, whichadditional information relates to the specific application of recordingand reproducing the MPEG information signal on/from the record carrier.In a specific example of the DVC format, the second-block sections cancomprise 77 bytes of information. In that situation, two transportpackets, from each of which the sync byte has been deleted, can bestored in second block sections of five signal blocks. Now, 11 bytes(=5×77-2×187) remain available in the five signal blocks. Those 11 bytescan be divided over the second block sections of the five signal blocksin various ways so as to obtain the third block sections. One such wayis that the first two bytes of all second block sections are availableas third block sections and that the last byte available can beconsidered as a third block section to indicate the boundary between theinformation of the two transport packets as stored in the five signalblocks.

In the above example, identification information identifying the signalblock as being the first signal block of the group of y signal blockscan be stored in a third block section of the first signal block in agroup of y signal blocks. Or, sequence number information ( sequencenumbers) relating to the sequence of the signal blocks can be stored inthe third block sections. This sequence number can also be identified asa continuity counter. The measures proposed result in a number ofadvantages.

The advantage of using identification information identifying a signalblock as being the first signal block in a group of y signal blocks, isthat the beginning of a group can be detected, which simplifies the readout of the data during reproduction.

One advantage using sequence numbers is that, when reproducing thesignal blocks, it can be decided upon retrieval of the sequence numbers,whether a signal block has been missed because of reproduction errors ornot, so that an error correction or concealment can be carried out.Another advantage is that one may shuffle the information to be storedin the signal blocks upon recording. Upon retrieval of the sequencenumbers it is possible to realize a corresponding deshuffling inresponse to the sequence numbers retrieved so as to obtain the originaldatastream.

Further, having sequence numbers included in the third block sections ofthe signal blocks, makes it possible to repeat signal blocks in the casethat a transport packet of the MPEG data stream stored in those signalblocks require a higher protection against errors that can occur duringthe recording and a subsequent reproduction process.

The recording arrangement as given in the opening paragraph may be alsocharacterized in that the information signal is an MPEG informationsignal in accordance with an MPEG format, the MPEG information signalcomprising subsequent transport packets, that the channel encoding meansare adapted to store each time information included in x transportpackets of the MPEG information signal in the second block sections of afirst group of y first signal blocks of said signal blocks of thechannel signal so as to enable a normal play mode using videoinformation stored in said first group of y first signal blocks during anormal play reproduction mode, the channel encoding means further beingadapted to retrieve a trick mode video signal from the MPEG informationsignal and being adapted to store said trick mode video signal in secondblock sections of a second group of z second signal blocks of saidsignal blocks of the channel signal so as to enable a trick play modeusing the video information stored in said second signal blocks, thatthe second block sections of at least one signal block in each first andsecond group of first and second signal blocks respectively comprise athird block section for storing identification information indicatingwhether the group comprises first signal blocks or second signal blocks,and that x, y and z are integers such that x≧1, y>1 and z>1.

More specifically, the information signal is an MPEG information signalin accordance with an MPEG format, the MPEG information signalcomprising subsequent transport packets, that the channel encoding meansare adapted to store each time information included in x transportpackets of the MPEG information signal in the second block sections of agroup of y signal blocks of the channel signal, that the second blocksections of at least those signal blocks in a group of y signal blocksthat comprises the start portion of a transport packet comprise a thirdblock section for storing sequence number information relating to atransport packet sequence number corresponding to the transport packethaving its start portion stored in the second block section of thesignal block, and that x and y are integers such that x≧1 and y>1.

This enables a reproduction in the reproducing arrangement in a normalplay mode using the first signal blocks and a reproduction in a trickplay mode using the second signal blocks, in response to the detectionof the information indicating the groups comprising first signal blocksor second signal blocks respectively.

The recording arrangement as given in the opening paragraph may also becharacterized in that the second block sections of all signal blocks ineach first and second group of first and second signal blocksrespectively comprise a third block section for storing identificationinformation indicating whether the group comprises first signal blocksor second signal blocks.

More specifically, the second block sections of a group of y signalblocks each comprise third block section for storing sequence numberinformation relating to a transport packet sequence number correspondingto the transport packet of which information is stored in said signalblock.

Storing a packet sequence number has its advantages if an MPEGdatastream is received having a constant bitrate, and comprising anumber of different video programs interleaved in the MPEG datastream.Generally, such datastream has a too high bitrate for recording thetotal datastream on the record carrier. The recording arrangement nowcomprises a program selector for retrieving one video program andcorresponding audio signal from the MPEG datastream so as to obtain theMPEG information signal for recording. As information corresponding toonly one video program is included in a MPEG transport packet, suchprogram selector selects only those transport packets from the MPEGdatastream that comprise information corresponding to said only onevideo program. That means that some packets of the original MPEGdatastream received are deleted. Upon reproduction however, an MPEGvideo signal in accordance with the MPEG standard, however nowcomprising only the one video program, should be regenerated. Suchregenerated datastream should have the transport packets that wereselected upon recording at the same location, that is in one or otherway, dummy packets corresponding to the packets deleted upon recordingmust be inserted in the regenerated datastream. Upon recording asequence number is added to each transport packet received, that is:also for the packets that will be deleted. The sequence numbers of thepackets that are selected and stored is stored in the third blocksection of the signal blocks in which a transport packet is stored. Uponreproduction, a sequence of numbers is retrieved, where subsequentnumbers will not necessarily be next higher numbers. In that situationone or more dummy packets must be inserted so as to regenerate thereplica of the original MPEG datastream.

The recording arrangement as given in the opening paragraph can furtherbe characterized in that the information signal is an MPEG informationsignal in accordance with an MPEG format, the MPEG information signalcomprising subsequent transport packets, the recording arrangementcomprising detection means for detecting the moment of receipt of thetransport packets and for generating timing information for eachtransport packet received, the timing information for a transport packetcorresponding to said moment of receipt of said transport packet, thatthe channel encoding means are adapted to each time store informationincluded in x transport packets of the MPEG information signal in thesecond block sections of a group of y signal blocks of the channelsignal, that the second block sections of at least those signal blocksin a group of y signal blocks that comprises the start portion of atransport packet comprise a third block section for storing the timinginformation for said transport packet having its start portion stored inthe second block section of the signal block, and that x and y areintegers such that x≧1 and y>1.

More specifically, the second block sections of a group of y signalblocks each comprise a third block section for storing the timinginformation corresponding to the transport packet which has informationstored in the second block section of said signal block. Storing timinginformation corresponding to transport packet requires that therecording arrangement is provided with detection means for detecting thetime of receipt of a transport packet. This measure has its advantagesif an MPEG datastream is received having a variable bitrate, andcomprising a number of different video programs interleaved in the MPEGdatastream. As has been said above, generally, such datastream has a toohigh bitrate for recording the total datastream on the record carrier.The recording arrangement now comprises a program selector forretrieving one video program with its corresponding audio signal fromthe MPEG datastream so as to obtain the MPEG information signal forrecording. As information corresponding to only one video program isincluded in a MPEG transport packet, such program selector selects onlythose transport packets from the MPEG datastream that compriseinformation corresponding to said only one video program. By detectingand storing the timing information corresponding to a transport packet,the reproducing arrangement will be capable of retrieving the timinginformation and recreate the MPEG information signal using said timinginformation.

It should be noted that the measures discussed above can be appliedsolely or in combination with one another in the recording arrangement.As a result, record carriers will be obtained having signal blocksstored in tracks on the record carrier, the signal blocks having a firstblock section which comprises a synchronisation signal and a secondblock section which comprises a number of channel bytes, x transportpackets of the MPEG information signal being stored in the second blocksections of a group of y signal blocks of the channel signal. Further inaccordance with the invention,

the second block section of at least the first signal block of the groupof y signal blocks comprise a third block section for storingidentification information identifying the signal block as being thefirst signal block of the group of y signal blocks, or

said identification information is sequence number information and thesecond block sections of a group of y signal blocks all comprise a thirdblock section for storing sequence number information relating to thesequence numbers of the signal blocks, or

the second block sections of the signal blocks each comprise a thirdblock section for storing identification information indicating whetherthe signal block comprise ` normal play` data or ` trick mode` data, or

the second block sections of at least those signal blocks in a group ofy signal blocks that comprises the start portion of a transport packetcomprise a third block section for storing identification informationrelating to a transport packet sequence number corresponding to thetransport packet having its start portion stored in the second blocksection of the signal block, or

the second block sections of at least those signal blocks in a group ofy signal blocks that comprises the start portion of a transport packetcomprise a third block section for storing the timing information forsaid transport packet having its start portion stored in the secondblock section of the signal block, or

third block sections comprise information resulting from a combinationof one or more of the measures listed above.

It will be apparent that a reproducing arrangement will be needed whichis adapted to each specific embodiment of the recording arrangement, soas to enable a reproduction of the MPEG information signal recorded onthe record carrier. Such reproducing arrangement is the subject of theclaims directed to the reproduction arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiments described hereafter. In thefigure description shows

FIG. 1 the track format of a record carrier of the DVC-type,

FIG. 2 schematically the contents of the video signal recording sectorin the track of FIG. 1,

FIG. 3 schematically the serial MPEG datastream and the format of thetransport packets included in the serial MPEG datastream,

FIG. 4 an example of the storage of two transport packets in five signalblocks,

FIG. 5 the contents of the track when having MPEG information recordedin it,

FIG. 6 an embodiment of the recording arrangement,

FIG. 7 an embodiment of the reproducing arrangement,

FIG. 8a an example of an original serial MPEG datastream having aconstant bitrate and packet rate, FIG. 8b the MPEG datastream that isrecorded and FIG. 8c the regenerated replica of the original serial MPEGdatastream,

FIG. 9 an embodiment of the `normal play` processing unit in therecording arrangement of FIG. 6,

FIG. 10 an example of a sequence of three groups of five signal blockseach,

FIG. 11 another example of a sequence of three groups of five signalblocks each,

FIG. 12 an example of the `normal play` processing unit in thereproducing arrangement of FIG. 7,

FIG. 13a an example of an original serial MPEG datastream having avariable bitrate and packet rate, FIG. 13b the MPEG datastream that isrecorded and FIG. 13c the regenerated replica of the original serialMPEG datastream,

FIG. 14 another embodiment of the `normal play` processing unit in therecording arrangement of FIG. 6,

FIG. 15 another embodiment of the `normal play` processing unit in thereproducing arrangement of FIG. 7,

FIG. 16 the record carrier and the read head scanning the record carrierduring a trick play mode,

FIG. 17 the sequence of signal blocks in a track forming the trick playarea.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows the format of the signals as they are recorded in a trackon a magnetic record carrier by means of a helical scan videorecorder ofthe DVC type. The left end of the track 1 in FIG. 1 is the start of thetrack and the right end of the track is the terminal pan of the track.The track comprises a number of track parts. The track part denoted byG1 is the pre-amble track pan. An example of the preamble track part G1has been described extensively in reference (1).

The track part G1 is followed by tracking tone recording part TP1, whichis denoted by ITI (insert timing information) track pan and whichcontains a tracking tone, synchronisation information and identification(or timing) information. Further explanation of the contents of the ITItrack can be found in reference (3).

The track part TP1 is followed by an edit gap G2. The edit gap G2 isfollowed by the track part TP2, which is the audio signal recordingsector and comprises digital audio information. The edit gap G3 isfollowed by a track part TP3 which is the video signal recording sectorand comprises digital video information. The edit gap G4 is followed bya track part TP4, denoted by INDEX and which comprises amongst otherssubcode information, such as absolute and/or relative time informationand a table of contents (TOC). The track is terminated by the track partG5. It can be said that the sequence order in which the pans TP1, TP2and TP3 occur in the tracks may be different.

The contents of the video signal recording sector TP3 is given in FIG.2. FIG. 2 in fact shows schematically a number of 149 horizontal lines,denoted by j=1 to j=149, having bytes of information stored in it. The149 lines are in fact 149 signal blocks (or sync blocks) that are storedsequentially in the video signal recording sector TP3.90 bytes ofinformation, denoted by i=1 to i=90, are stored in each signal block.

The first two bytes (i=1 and i=2) of each signal block form asynchronisation pattern of 2 bytes long. The following three bytes ineach signal block form an ID code, comprising amongst others informationwhich indicates the sequence number of the signal block in the videosignal recording pan TP3. The last eight bytes in the signal blocks formhorizontal parity information. Vertical parity information is stored inthe storage locations i=6 to i=82 inclusive of the last 11 signalblocks.

Bytes of video signal information are stored in the storage locationsi=6 to i=82 inclusive of the signal blocks having the sequence numbersj=3 to j=137 inclusive. Bytes of auxiliary data are stored in thestorage locations i=6 to i=82 inclusive of the signal blocks having thesequence numbers j=1, 2 and 138. The signal blocks are storedsequentially in the video signal part TP3, starting with the signalblock denoted y=1, followed by the signal block denoted j=2, and so onuntil the signal block denoted j=149.

The auxiliary data for storage in the signal blocks denoted j=1, 2 and138 can be teletext data or control data.

It should be noted here that it can be specified that the auxiliary datawill be stored in a different location in the memory. Reference is madein this respect to document (1), FIG. 13, where the auxiliary data isstored in the memory part denoted by III.

FIG. 3 shows schematically the MPEG datastream applied to a recordingarrangement in accordance with the invention. The MPEG datastreamcomprises subsequent transport packets, denoted by . . . , P_(k-1),P_(k), P_(k+1), . . . . The packets each comprise a packet headerportion PH of 4 bytes long and a body portion of 184 bytes long. Thetransport packets can be transmitted in a datastream having a constantbitrate. This means that the packets are equally long, viewed in time,and are received at a fixed packet rate. The transport packets may alsobe transmitted in a datastream having a variable bitrate. In thissituation, the packets need not be of the same length, viewed in time,and may be received with a variable packet rate. The first byte in thepacket header PH is a sync byte. The sync byte is identical for all thetransport packets. The other three bytes in the header comprise IDinformation, such as a packet identifier. For a further explanation ofthe contents of the ID information, reference is made to document (4) inthe list of references, more specifically chapter V, paragraph 5.1 onpage 27.

The body portion of the transport packets comprise each 184 bytes forstoring the video and audio information that should be transmitted inaccordance with the MPEG format. The body portion of one transportpacket can store either audio information corresponding to a certainvideo signal, or the video signal. Further, in the case that a number ofvideo programs are transmitted via the MPEG datastream, the body portionstores a video signal corresponding to one of such video programstransmitted.

The invention now aims at recording the video signal, and thecorresponding audio signal as may be appreciated, corresponding to oneof those video programs transmitted via the MPEG data stream on therecord carrier having the track format disclosed in FIG. 1 and 2.Information stored in the transport packets should be stored in thesignal blocks, more specifically, in the 135 signal blocks denoted j=3to j=137 in the video signal recording part TP3 of a track. The two syncbytes, denoted i=1 and 2, the ID information in the form of the three IDbytes denoted i=3, 4 and 5, as well as the 8 horizontal parity bytes,denoted by i=83 to 90, in those signal blocks are required for a correctrecording and reproduction. As a consequence, only the 77 bytes, denotedby i=6 to 82, in the signal blocks denoted by j=3 to 137, are availablefor the storage of the transport packets of the MPEG information. Thepart of the signal blocks formed by the 77 bytes i=6 to 82 is defined asbeing the second block sections of the signal blocks.

As synchronization during recording and reproduction is assured by meansof the sync words in each of the signal blocks, there is no need fortransmitting the sync bytes of the transport packets via the recordcarrier. So, before storing the information comprised in the transportpackets in the second block sections of the signal blocks denoted by j=3to 135, the sync byte of all the transport packets is thrown away. As aresult only 187 bytes of information should be stored in the signalblocks for each transport packet.

A simple calculation makes clear that two transport packets can bestored in five signal blocks, and that 11 bytes remain available for thestorage of other information. FIG. 4 gives an example of how the twotransport packets can be stored in the second block sections of thegroup of five signal blocks, denoted SB1 to SB5 in FIG. 4. FIG. 4 onlyshows the contents of the second block sections of length of 77 bytesincluded in the signal blocks. As can be seen in FIG. 4, the 11 bytesare divided over the group of five signal blocks such that each secondblock section comprises a third block section TB3.1 to TB3.5, of twobytes long at the beginning of the second block sections of the fivesignal blocks SB1 to SB5 respectively, and a third block section in theform of one byte, denoted by FB, is available in the third signal blockSB3. The 187 bytes of the first transport packet are stored in thesignal blocks SB1, SB2 and SB3, where the three ID bytes of the packetheader of the first transport packet, indicated by TH1, are stored firstin the signal block SB1, directly after the third block section TB3.1,and next the first 72 first bytes in the body of the first transportpacket are stored thereafter in the second block section of the signalblock SB1. The next 75 bytes in the body of the first transport packetare stored in the second block section of the signal block SB2, afterthe third block section TB3.2, and the last 37 bytes in the body of thefirst transport packet are stored in the second block section of thesignal block SB3, after the third block section TB3.3.

Next comes the byte FB, which indicates the boundary between theinformation of the first and second transport packets stored in thegroup of five signal blocks. The 187 bytes of the second transportpacket are stored in the signal blocks SB3, SB4 and SB5, where the threeID bytes of the packet header of the second transport packet, indicatedby TH2, are stored first in the signal block SB3, directly after thebyte FB. Next the first 34 first bytes in the body of the secondtransport packet are stored thereafter in the second block section ofthe signal block SB3. The next 75 bytes in the body of the secondtransport packet are stored in the second block section of the signalblock SB4, after the third block section TB3.4, and the last 75 bytes inthe body of the second transport packet are stored in the second blocksection of the signal block SB5, after the third block section TB3.5.

It should be noted that also another spreading of the 11 available bytesover the five signal blocks is possible. As an example, the 11 bytescould have been split into two third block sections, the one third blocksection having as an example 6 bytes and being located at the beginningof the first signal block SB 1, and the other third block section of 5bytes long being located in the third signal block and indicating theboundary between the two transport packets stored in the five signalblocks. Another example could have been to have a third block sectionlocated at the beginning of the signal blocks SB1 and SB3 and anotherthird block section in the third signal block SB3, indicating theboundary between the two transport packets stored in the five signalblocks, where the third block section in the signal block SB1 can haveeg. 4 bytes, the first third block section in the signal block SB3 eg. 3bytes and the third block section in signal block SB3 indicating thesaid boundary being eg. 4 bytes long.

The third block sections TB3.1 to TB3.5 can be used for the storage ofadditional information. As a first example, the third block sectionTB3.1 can include an indication identifying the signal block SB1 asbeing the first signal block in a group of five signal blocks. This canbe realized by storing in one specific bit location in the third blocksection TB3.1 a bit value of a certain polarity, such as `0` or `1` Inthe same bit locations in the third block sections TB3.2 to TB3.5 a bitvalue of the opposite polarity should be stored. In another example,sequence number information, eg. sequence numbers running from 1 to 5can be stored in the third block sections TB3.1 to TB5 respectively, ofthe group of five signal blocks, where the third block section TB3.1 hasthe sequence number `1` and the third block section TB3.5 has thesequence number `5` stored in them. Three specific bit locations in thethird block sections TB3.1 to TB3.5 are required to stored the sequencenumbers. The sequence numbers can however also run across the groupboundaries so as to identify a larger sequence of signal blocks, egwithin one track, or even in more than one track.

In another example, one specific bit location in the third blocksections TB3.1 to TB3.5 of a group of five signal blocks can be used tostore either a bit value of one polarity, such as `0` or `1`, so as toindicate that the video dam included in the signal block is so-called`normal play` data, or a bit value of the opposite polarity, so as toindicate that the video dam included in the signal block is so-called`trick play` video data. The use of the `normal play` video dam and`trick play` video dam will be explained later.

In again another example, sequence numbers are generated in response totransport packets in the MPEG datastream that is received. As has beenexplained earlier, such MPEG datastream can include more than one videoprograms. As the bitrate of the MPEG datastream is normally higher thanthe bitrate of the signal that can be recorded, only one video programmay be selected from the serial MPEG datastream for recording. Selectionof one video program means selection of transport packets out of thedatastream of the MPEG datastream that comprise the information relatingto said video program, and deleting the other packets. Consequently theserial array of transport packets that will be recorded have sequencenumbers that not necessarily are next higher numbers, as those sequencenumbers of the transport packets deleted are not present. When storingthe sequence numbers in the third block sections, those sequence numberscan be retrieved upon reproduction. By checking the subsequent sequencenumbers retrieved, it can be established whether the original MPEGdatastream applied to the recording arrangement, originally includeddeleted transport packets between two transport packets reproduced. Ifso, a replica of the original MPEG datastream can be regenerated byinserting one or more dummy packets between the two transport packetsreproduced.

In a related example, timing information is stored in the third blocksections, for the same reason as given above, namely for regenerating areplica of the original MPEG datastream, in the case that suchdatastream is a datastream having a variable bitrate.

It will be clear that also a combination of the additional informationdescribed above can be included in the 11 bytes available for thestorage of such information in a group of five signal blocks.

As an example, it has been made clear above that a 3-bit word is neededin the third block sections to indicate the sequence numbers of thesignal blocks in the group of five signal blocks. More specifically, the3-bit words `000`, `001`, `010`, `011` and `100` could have been used toidentify the sequence. That means that the 3-bit words `101`, `110` and`111` remain available for a further identification. As an example, the3-bit words `101` and `110` could be used to identify either `normalplay` data or `trick mode` data.

FIG. 5 shows the track format of the track if the MPEG information hasbeen stored in the second block portions of the signal blocks of thetrack portion TP3 of FIG. 1, now denoted by track portion TP3'. FIG. 5shows the first two signal blocks (j=1,2) in the track portion TP3' thatstill includes the auxiliary data, followed by 135 signal blocks (j=3 toj=137) now comprising the MPEG information and the additionalinformation described above. Next one signal block (j=138) alsocomprising the auxiliary data, followed by 11 signal blocks comprisingthe parity information. The storage of the MPEG information and theadditional information in the 135 signal blocks may require anadditional error encoding step to be carried out on the saidinformation, resulting in additional parity information that should alsobe stored in a track. As the MPEG information, which includes videoinformation and corresponding audio information, is stored in the signal135 blocks in the track portion TP3', there is no need for storing audioinformation in the track portion TP2 of FIG. 1. This portion, nowdenoted by TP2' in FIG. 5, can be used to store the parity informationresulting from the additional error encoding step.

FIG. 6 shows schematically an embodiment of the recording arrangement.The recording arrangement comprises an input terminal 11 for receivingthe MPEG serial datastream for recording transport packets included inthe datastream in the signal blocks of the track portions TP3' of thetracks. The input terminal 11 is coupled to an input 12 of a `normalplay` processing unit 14. Optionally, a `trick play` processing unit 16is provided having an input 17 also coupled to the input terminal 11.Outputs 19 and 20 of the `normal play` processing unit 14 and the `trickplay` processing unit 16 (if present) are coupled to correspondinginputs of a multiplexer 22. It will be clear that in the absence of the`trick play` processing unit 16, also the multiplexer 22 will be absent.

An auxiliary signal generator 24 is present for supplying the auxiliarysignal information for storage in the signal blocks denoted by j=1,2 and138, see FIG. 2. Outputs of the multiplexer 22 and the generator 24 arecoupled to corresponding inputs of an error correction encoder unit 26.The error correction encoder unit 26 is capable of carrying out a firsterror correction encoding step, denoted ECC3 and a second errorcorrection encoding step, denoted ECC2. Next a third error correctionencoding step, denoted ECC1, is carried out in an error correctionencoder unit 28.

The recording arrangement further comprises a generator 30 for addingthe ID information in the bytes i=3, 4 and 5 of the signal blocks, seeFIG. 2, for adding the index information for storage in the trackportion TP4, see FIG. 5, and the gap information for realizing the gapsG1 to G5, see FIG. 5. After combination of the signals in the combiningunit 32, the combined signal is applied to a unit 34, in which anencoding is carried out where each time 24-bit words of the incomingbitstream are converted into 25-bit words, where a sync word is added soas to obtain the first two bytes (i=1,2) in the signal blocks and wherethe ITI information is added for storage in the track portion TP1.

The 24-to-25 encoding carried out in the encoding unit 34 is well knownin the art. Reference is made in this respect to U.S. Pat. No.5,142,421, document (5) in the list of references. This document also away of adding the sync word to the datastream.

An output of the encoding unit 34 is coupled to an input of a writingunit 36, in which the datastream obtained with the encoding unit 34 isrecorded in the slant tracks on the record carrier, by means of at leastone write head 42.

The first error correction encoding step, denoted ECC3, is required soas to realize the additional error protection of the MPEG information tobe recorded on the record carrier, and results in parity informationthat will be stored in the track portion TP2', as has been explainedpreviously. The second error correction encoding step, denoted ECC2,results in the vertical parity information that will be stored in the 11signal blocks (j=139 to 149) of the track portion TP3', see the FIGS. 2and 5. The third error correction encoding step, denoted ECC1, resultsin the horizontal parity information that will be stored in the last 8bytes of the signal blocks in the track portion TP3', see the FIG. 2 and5.

Before a further description of the `normal play` processing unit 14 andthe `trick play` processing unit 16 of the recording arrangement of FIG.6 will be given, first a schematic description of the reproducingarrangement will be given. This has the advantage that, when furtherdescribing certain measures applied in the processing units 14 and 16, adirect relation can be given to the advantages and consequences of thosemeasures during reproduction.

FIG. 7 shows schematically an embodiment of a reproduction arrangementfor reproducing information from the record carrier 40 obtained with therecording arrangement of FIG. 6. The reproduction arrangement comprisesa reading unit 50, having at least one reading head 52 for readinginformation from the slant tracks on the record carrier 40. An output ofthe reading unit 50 is coupled to an input of a decoding unit 54, whichcarries out a 25-to-24 decoding on the signal read out, so as to convert25-bit words in the incoming datastream into 24-bit words. Next, afterhaving selected out in the selector unit 56 all those information thatis not required for recreating a replica of the original MPEGdatastream, an error correction is carried out in the error correctionunit 58. It will be clear that the error correction carried out hasthree steps. One error correction step based on the ECC1, using thehorizontal parities, see FIG. 2, a second error correction step based onECC2, using the vertical parities, and a third error correction stepbased on ECC3, using the parity information stored in the track portionTP2', see FIG. 5.

The output terminal of the error correction unit 58 is coupled to aninput of a `normal play` processing unit 60. Optionally, a `trick play`processing unit 62 is provided having an input also coupled to theoutput of the error correction unit 58. Outputs 64 and 65 of the `normalplay` processing unit 60 and the `trick play` processing unit 62 (ifpresent) are coupled to corresponding terminals a and b respectively ofa switch 66, a c-terminal of which is coupled to an output terminal 68.It will be clear that in the absence of the `trick play` processing unit62, also the switch 66 will be absent. If the reproducing arrangement isswitched into a `normal play` reproduction mode, this means that therecord carrier is transported at a nominal speed, that the `normal play`processing unit 60 is enabled and the switch 66 is switched into theposition a-c. If the reproducing arrangement is switched into a `trickplay` reproduction mode, also called `feature mode`, this means that therecord carrier is transported at a speed other than the nominal speed,that the `trick play` processing unit 62 is enabled and the switch 66 isswitched into the position b-c.

Now a further discussion will be given of the processing units 14 and 16of FIG. 6, in combination with the processing units 60 and 62 of FIG. 7.

It is assumed that the recording arrangement is capable of selecting onevideo program and its corresponding audio signal from the serial MPEGdatastream that is applied to the input terminal 11, in response to aselection signal supplied to the arrangement by a user. As has been saidearlier, only those transport packets in the serial MPEG stream shouldbe selected that include information relating to the video programselected. FIG. 8a shows the serial MPEG datastream as a function of timecomprising the transport packets denoted P_(k). It should be noted thatthe transport packets of the MPEG datastream do not comprise a packetnumber. The packet number k, given to the packets in FIG. 8a aretherefore the numbers that will be generated by the packet numbergenerator 86 of FIG. 9 that will be discussed later.

Selecting only those packets of the packets P_(k) of FIG. 8a thatinclude information relating to the video program selected means, as anexample, that the packets P_(k-4), P_(k-1), P_(k), P_(k+2), P_(k+4),P_(k+8) will be selected and that the intermediate packets will bethrown away. As a result, a datastream has been obtained in therecording arrangement for recording on the record carrier, as shown inFIG. 8b, which shows the datastream as a function of time. No conclusionshould be drawn from the timing in the time scales of FIG. 8a and 8b,nor from the relative location between the time scales in FIG. 8a and8b. This for the reason that, as has been said previously, the bitrateofthe original MPEG datastream (FIG. 8a) is different from (higher than)the bitrate with which the selected transport packets will be recordedon the record carrier.

An embodiment of the `normal play` processing unit 14 for recording adatastream as shown in FIG. 8b is shown schematically in FIG. 9. Theembodiment denoted 14' in FIG. 9, comprise a selector unit 76 having aninput coupled to the input 11 of the unit 14'. The selector unit 76 hasanother input 78 for receiving the selection signal supplied by theuser. An output 79 of the selector unit 78 is coupled to the input of async stripper 80, whose output is coupled to a signal combining unit 82.Further, an output 81 of the selector 76 is coupled to a control input83 of the combining unit 82, for supplying a control signal to thecombining unit 82.

The input 11 is further coupled to an input of a packet detector 84,which has an output coupled to an input of a packet number generator 86.An output of the generator 86 is coupled to a second input of thecombining unit 82.

The selector 76 selects the transport packets P_(k-4), P_(k-1), P_(k),P_(k+2), P_(k+4), P_(k+8) from the serial MPEG datastream applied to theinput 11 in response to the selection signal received via the input 78.The packets selected are applied to the sync stripper 80, in which thefirst sync byte in the packet header PH, see FIG. 3, is deleted from thepackets, in accordance with a description given previously. The packetdetector 84 detects the receipt of each packet in the original serialMPEG data stream applied to the input 11 and generates a clock impulsefor each packet detected. The generator 86 includes a counter thatcounts up under the influence of the clock impulses applied to thegenerator 86. As a consequence a next higher count number is applied tothe output for each clock impulse received. At the output 87 of thegenerator 86 thus appear count numbers . . . . k-4, k-3, k-2, k-1,k,k+1, k+2, k+3, k+8, . . . Under the influence of the control signalapplied to the control input 83 of the combining unit 82, the controlunit combines the packets P_(k-4), P_(k-1), P_(k), P_(k+2), P_(k+4),P_(k+8) selected by the selector 76 as well as the count numbers k-4,k-1, k, k+2, k+4, k+8 out of the count number stream supplied by thepacket number generator 86 for storage into the signal blocks.

FIG. 10 shows an example how the transport packets and the correspondingpacket numbers can be stored in the groups of five signal blocks. FIG.10 shows three subsequent groups of five signal blocks, denoted G1, G2and G3 in which the information is stored. In the third block sectionTB3.1 of the first signal block SB1 of the group G1, the packet numberk-4 is stored and the information comprised in the packet P_(k-4) isstored thereafter in the signal blocks SB1, SB2 and SB3 of the group G1.In the third block section denoted FB of the third signal block SB3 ofthe group G1, the packet number k-1 is stored and the informationcomprised in the packet P_(k-1) is stored thereafter in the signalblocks SB3, SB4 and SB5 of the group G1. In the third block sectionTB3.1 of the first signal block SB1 of the group G2, the packet number kis stored and the information comprised in the packet P_(k) is storedthereafter in the signal blocks SB1, SB2 and SB3 of the group G2. In thethird block section denoted FB of the third signal block SB3 of thegroup G2, the packet number k+2 is stored and the information comprisedin the packet P_(k+2) is stored thereafter in the signal blocks SB3, SB4and SB5 of the group G2. In the third block section TB3.1 of the firstsignal block SB1 of the group G3, the packet number k+4 is stored andthe information comprised in the packet P_(k+4) is stored thereafter inthe signal blocks SB1, SB2 and SB3 of the group G3. In the third blocksection denoted FB of the third signal block SB3 of the group G3, thepacket number k+8 is stored and the information comprised in the packetP_(k+8) is stored thereafter in the signal blocks SB3, SB4 and SB5 ofthe group G3. As long as the number of bits of the packet number issmaller than or equal to 8, the packet number will fit in the thirdblock section FB, which is 1 byte long.

Another example of storing the packet numbers in the third blocksections is given in FIG. 11. In the third block sections TB3.1, TB3.2and TB3.3 of the signal blocks SB1, SB2 and SB3 respectively of thegroup G1, the packet number k-4 is stored and the information comprisedin the packet P_(k-4) is stored in the signal blocks SB1, SB2 and SB3 ofthe group G1, as explained previously with reference to FIG. 4. In thethird block section denoted FB of the third signal block SB3 of thegroup G1, as well as in the third block sections TB3.4 and TB3.5 of thesignal blocks SB4 and SB5 of the group G1, the packet number k-1 isstored and the information comprised in the packet P_(k-1) is stored inthe signal blocks SB3, SB4 and SB5 of the group G1, as explainedpreviously with reference to FIG. 4. In the third block sections TB3.1,TB3.2 and TB3.3 of the signal blocks SB1, SB2 and SB3 respectively ofthe group G2, the packet number k is stored and the informationcomprised in the packet P_(k) is stored in the signal blocks SB1, SB2and SB3 of the group G2. In the third block section denoted FB of thethird signal block SB3 of the group G2, as well as in the third blocksections TB3.4 and TB3.5 of the signal blocks SB4 and SB5 respectivelyof the group G2, the packet number k+2 is stored and the informationcomprised in the packet P_(k+2) is stored in the signal blocks SB3, SB4and SB5 of the group G2. In the third block sections TB3.1, TB3.2 andTB3.3 of the signal blocks SB1, SB2 and SB3 of the group G3, the packetnumber k+4 is stored and the information comprised in the packet P_(k+4)is stored in the signal blocks SB1, SB2 and SB3 of the group G3. In thethird block section denoted FB of the third signal block SB3 of thegroup G3, as well as in the third block sections TB3.4 and TB3.5 of thesignal blocks SB4 and SB5 of the group G3, the packet number k+8 isstored and the information comprised in the packet P_(k+) 8 is stored inthe signal blocks SB3, SB4 and SB5 of the group G3.

Instead of storing the packet number k-4 in the third block sectionTB3.3 of the signal block SB3 in group G1, one could have stored thepacket number k-1 in said third block section. Instead of storing thepacket number k in the third block section TB3.3 of the signal block SB3in group G2, one could have stored the packet number k+2 in said thirdblock section. Instead of storing the packet number k+4 in the thirdblock section TB3.3 of the signal block SB3 in group G3, one could havestored the packet number k+8 in said third block section.

FIG. 12 schematically shows an embodiment of the `normal play`processing unit 60 of the reproducing arrangement of FIG. 7, forregenerating a replica of the original MPEG datastream of FIG. 8a fromthe datastream as shown in FIG. 8b, using the packet number informationalso stored in the signal blocks, in the way described above. Theregenerated replica of the MPEG datastream is shown in FIG. 8c. Theembodiment of the `normal play` processing unit of FIG. 12, denoted by60', comprises a demultiplexer 90 having its input coupled to the input59 of the processing unit 60' for receiving the subsequent groups ofsignal blocks, such as the groups G1, G2 and G3 of FIG. 10 or 11, andfor retrieving therefrom the packets that are supplied to an output 91and for retrieving the array of packet numbers . . . k-4, k-1, k, k+2,k+4, k+8 . . . from the third block sections in the signal blocks, andfor supplying the said array of packet numbers to an output 92. Thepackets retrieved are supplied to a sync adder circuit 94 in which theone byte long packet sync signal is reinserted as first byte in all thepackets. The packets thus obtained are supplied to an input 95 of acombining unit 96. The output 92 of the demultiplexer 90 is coupled toinputs 97 and 98 of the combining unit 96 and a dummy packet generator100 respectively. An output 102 of the dummy packet generator 100 iscoupled to an input 103 of the combining unit 103. An output 105 of thecombining unit 96 is coupled to the output 64 of the `normal play`processing unit 60'.

Let us now assume that the packet P_(k-4) and the packet number k-4 areretrieved from the first group G1 of five signal blocks, and are appliedto the combining unit 96 and the dummy packet generator 100. Thisresults in the packet P₋₄ being supplied to the output 105 by thecombining unit 96. Next, the packet P_(k-1) and the packet number k-1are retrieved from the group G1 and are applied to the combining unit 96and the dummy packet generator 100. It is established, by means of acomparator and/or a subtractor (not shown), that the packet number k-1is not the next higher packet number of the packet number k-4, receivedpreviously and that two packet numbers are missing. As a result, thedummy packet generator 100 generates twice a dummy packet of the samelength as the other packets in the datastream, and the combining unit 96inserts those two dummy packets in the serial datastream, directly afterthe packet P₋₄, see FIG. 8c. Next, the combining unit 96 inserts thepacket P_(k-1) into the serial datastream.

It should be noted here, that there is no specific need for thegenerator 100 to be explicitly a dummy packet generator. It is alsopossible that the generator 100 is a dummy info generator that generatesdummy info of a certain length in time, this length of time being equalto the length of time of a packet or equal to a multiple of the lengthof time of a packet.

The packet P_(k) is the next packet that is retrieved by thedemultiplexer 90, and the packet is supplied, after the addition of thesync byte, to the input 95 of the combining unit 96. The packet number kis supplied to the inputs 97 and 98 of the combining unit 96 and thedummy packet generator 100. As the packet number k is the next higherpacket number to packet number k-1, no dummy packet is generated, andthe packet P_(k) is supplied to the output 105.

Next the packet P_(k+2) is retrieved. After comparison of the packetnumber k+2 with the previous packet number k retrieved, it appears thatone dummy packet must be inserted in the serial datastream. Next, thepacket P_(k+2) is added to the datastream, see FIG. 8c. This process iscontinued for the other packets, so as to obtain the regenerated replicaof the MPEG datastream of FIG. 8c. When comparing FIG. 8a and 8c, itwill be clear that FIG. 8c shows an MPEG serial datastream having thesame bitrate and packet rate as the MPEG datastream of FIG. 8a. Thisdatastream can now be applied to a standard MPEG decoder which iscapable of decoding the one video program selected by the recordingarrangement during recording, from the MPEG datastream of FIG. 8c.

FIG. 13a shows an MPEG serial datastream as a function of time, thedatastream comprising packets P_(k) having a variable length, and thebitrate in the datastream also being variable. It should be noted thatthe transport packets of the MPEG datastream do not comprise a packetnumber. The packet number k, given to the packets in FIG. 13a aretherefore only added in this description for identification purposes.FIG. 14 shows schematically an embodiment of the `normal play`processing unit 14 for recording one video program that is included inthe serial datastream as shown in FIG. 13a. The embodiment denoted 14"in FIG. 14 shows large resemblances with the embodiment of FIG. 9. Theembodiment 14" differs from the embodiment of FIG. 9, in that, insteadof the packet number generator 86, now a timing detector 110 is present,having its input coupled to the output of the detector 84, and havingits output 111 coupled to the input 112 of the combining unit 82.

Selecting only those packets of the packets P_(k) in the serialdatastream of FIG. 13a that include information relating to one videoprogram that will be selected again means, as an example, that thepackets P_(k-4), P_(k) ₋₁, P_(k), P_(k+2), P_(k+4), P_(k+8) will beselected and that the intermediate packets will be thrown away. FIG. 13bshows the datastream of the selected packets that will be stored in thegroups of signal blocks, as already has been explained with reference tothe FIGS. 10 and 11. It should be noted also here, that there is no timerelationship between the time axes in the FIGS. 13a and 13b. Further, itshould be noted that, although the packets in the datastream of FIG. 13ahave unequal length, they all include 188 bytes of information.Therefore, the packets selected and displayed in FIG. 13b have beenshown as packets having an equal length.

The embodiment of FIG. 14 receives the datastream of FIG. 13a andselects therefrom the packets P_(k-4), P_(k-1), P_(k), P_(k+2), P_(k+4),P_(k+8). The packet detector 84 detects the receipt of each packet inthe original serial MPEG data stream applied to the input 11 andgenerates a clock impulse for each packet detected. In response to eachclock impulse received, the timing detector 110 detects the timeinstants t_(k), see FIG. 13a, of occurrence of the packets P_(k). Thusat the output 111 of the detector 110 appear the time instants . . .t_(k-4), t_(k-3), t_(k-2), t_(k-1), t_(k), . . . etc. Moreover the timedetector 110 detects the lengths of the time intervals dt_(k) betweentwo subsequent time instants, where dt_(k) equals the time intervalt_(k+1) -t_(k). Those time interval values dt_(k) are also applied tothe output 111. Under the influence of the control signal applied to thecontrol input 83 of the combining unit 82', the control unit combinesthe packets P_(k-4), P_(k-1), P_(k), P_(k+2), P_(k+4), P_(k+8) selectedby the selector 76 as well as the time instants and corresponding timeintervals t_(k-4), dt_(k-4), t_(k-1), dt_(k-1), t_(k), dt_(k), t_(k+2),dt_(k+2), t_(k+4), dt_(k+4), t_(k+8), dt_(k+8) out of the informationstream supplied by the timing detector 110 for storage into the signalblocks.

The storage of the transport packets in the signal blocks will becarried out in the same way as discussed above with reference to theFIGS. 10 and 11. The storage of the timing information in the thirdblock sections can be as follows.

In the third block section TB3.1 of the first signal block SB 1 of thegroup G1 of FIG. 10, the timing information t_(k-4) and dt_(k-4) isstored. In the third block section denoted FB of the third signal blockSB3 of the group G1, the timing information t_(k-1) and dt_(k-1) isstored. In the third block section TB3.1 of the first signal block SB1of the group G2, the timing information t_(k) and dt_(k) is stored. Inthe third block section denoted FB of the third signal block SB3 of thegroup G2, the timing information t_(k+2) and dt_(k+2) is stored. In thethird block section TB3.1 of the first signal block SB1 of the group G3,the timing information t_(k+4) and dt_(k+4) is stored. In the thirdblock section denoted FB of the third signal block SB3 of the group G3,the timing information t_(k+8) and dt_(k) +8 is stored.

It may be so that the third block section TB3.1 in the first signalblock SB1 in the groups and/or the third block section FB in the thirdsignal block SB3 in the groups is/are too small for storing the timinginformation. In that case, the timing information can be storedsomewhere else, or can be stored partly in the third block section TB3.1and FB and partly somewhere else, see below.

In accordance with the example of FIG. 11, the timing informationt_(k-4) and dt_(k-4) is stored in the third block sections TB3.1, TB3.2and TB3.3 of the signal blocks SB1, SB2 and SB3 respectively of thegroup G1. The storage of the timing information can be carded out oncein the total storage capacity of the third block sections TB3.1, TB3.2and TB3.3 or can be repeated at least once. As an example, the timinginformation t_(k-4) and dt_(k-4) is stored in each of the third blocksections TB3.1, TB3.2 and TB3.3. The timing information t_(k-1) anddt_(k-1) can be stored in the third block sections FB, TB3.4, and TB3.5of the signal blocks SB3, SB4 and SB5 respectively of the group G1. Thestorage of the timing information can be carded out once in the totalstorage capacity of the third block sections FB, TB3.4 and TB3.5 or canbe repeated at least once. As an example, the timing information t_(k-4)and dt_(k-4) is stored in each of the third block sections TB3.4 andTB3.5. It may be possible to store the timing information for the packetP₋₁ in the third block section TB3.3. It is further possible to storethe timing information in the third block sections TB3.4 and TB3.5, andnot in the block section FB.

The timing information for the packet P_(k) can be stored in the thirdblock sections of the group G2 in the same way as the timing informationfor the packet P_(k-4) has been stored in the third block sections ofthe group G1. The timing information for the packet P_(k+2) can bestored in the third block sections of the group G2 in the same way asthe timing information for the packet P_(k-1) has been stored in thethird block sections of the group G1.

The timing information for the packet P_(+4k) can be stored in the thirdblock sections of the group G3 in the same way as the timing informationfor the packet P_(k-4) has been stored in the third block sections ofthe group G1. The timing information for the packet P_(k+8) can bestored in the third block sections of the group G3 in the same way asthe timing information for the packet P_(k-1) has been stored in thethird block sections of the group G1.

FIG. 15 schematically shows an embodiment of the `normal play`processing unit 60 of the reproducing arrangement of FIG. 7, denoted60", for regenerating a replica of the original MPEG datastream of FIG.13a from the datastream as shown in FIG. 13b, using the timinginformation also stored in the signal blocks, in the way describedabove. The regenerated replica of the MPEG datastream is shown in FIG.13c. The embodiment 60" of FIG. 12 shows a large resemblance with theprocessing unit of FIG. 12. The demultiplexer 90' is again adapted toretrieve the packets from the subsequent groups of signal blocks, and tosupply the packets to the output 91. The demultiplexer 90' is furtheradapted to retrieving the timing information t_(k) and dt_(k) from thethird block sections in the signal blocks, and for supplying the saidtiming information to the output 92. A sync byte is added to each packetin the sync adder 94. The packets thus obtained are supplied to theinput 95 of the combining unit 96'. The output 92 of the demultiplexer90 is coupled to inputs 97 and 98 of the combining unit 96' and a dummyinfo generator 100' respectively for supplying the timing information tothe combining unit 96' and the generator 100'.

Let us now assume that the packet P_(k-4) and the corresponding timinginformation are retrieved from the first group G1 of five signal blocks,and are applied to the combining unit 96' and the dummy packet generator100'. This results in the packet P_(k-4) being supplied to the output105 by the combining unit 96', in response to the timing information.The length of the packet P_(k-4) will be equal to dt_(k-4), and thepacket will be applied to the output 105 at a time instant correspondingto t_(k-4). Next, the packet P_(k-1) and the timing informationcorresponding to the packet P_(k-1) are retrieved from the group G1 andare applied to the combining unit 96' and the dummy packet generator100'. It is established, by means of a comparator and/or a subtractor(not shown), that the time instant t_(k-1) is not equal to t_(k-4)+dt_(k-4). Consequently at least one packet following the packet P_(k-4)has been thrown away during recording. As a result, the dummy infogenerator 100' generates a block of dummy information so as to fill thegap between the end of the packet P_(k-4), at the time instant t_(k-4)+dt_(k-4), and the time instant t_(k-1), see FIG. 13c.

Next, the combining unit 96' inserts the packet P_(k-1) having thelength dt_(k-1) into the serial datastream.

The packet P_(k) is the next packet that is retrieved by thedemultiplexer 90, and the packet is supplied, after the addition of thesync byte, to the input 95 of the combining unit 96'. The timinginformation corresponding to the packet P_(k) is supplied to the inputs97 and 98 of the combining unit 96 and the dummy info generator 100'. Ast_(k) equals t_(k-1) +dt_(k-1), no dummy information need to be isgenerated, and the packet P_(k) is supplied to the output 105.

Next the packet P_(k+2) is retrieved. After comparison of t_(k+2) witht_(k) +dt_(k), it is established that a gap is present that need to befilled with dummy information generated by the generator 100'. Next, thepacket P_(k+2) having a length dt_(k+2) is added to the datastream, seeFIG. 13c. This process is continued for the other packets, so as toobtain the regenerated replica of the MPEG datastream of FIG. 13c. Whencomparing FIG. 13a and 13c, it will be clear that FIG. 13c shows an MPEGserial datastream having the same (variable) bitrate and packet rate asthe MPEG datastream of FIG. 13a. This datastream can now be applied to astandard MPEG decoder which is capable of decoding the one video programselected by the recording arrangement during recording, from the MPEGdatastream of FIG. 13c having the variable bitrate and packet rate.

Now, other information will be described that can be inserted in thefree space in the groups of signal blocks alone or together with thepacket number information and or the timing information described above.

One example of such other information is the information identifying asignal block in a group of y(=5) signal blocks to be the first signalblock in the group of signal blocks. Such information can be stored inthe third block sections TB3.1 of the signal blocks SB1 in the groupsG1, G2 and G3, in the FIGS. 10 and 11.

Another example of such other information is the inclusion of a signalblock number in the third block sections of the signal blocks, such asin the situation of FIG. 11. Signal block numbering can be carried outwithin a group, so that in the example of FIG. 11, the numbers 1 to 5are stored in the third block sections TB3.1 to TB3.5 respectively ofthe signal blocks SB1 to SB5 in each group. Signal block numbering canalso be realized for a larger number of signal blocks, belonging to morethan one group of signal blocks. One could imagine that all the signalblocks in one track have a unique signal block number stored in thethird block sections of the signal blocks. Now, all the signal blocks ina track can be identified by their unique signal block number.

Signal block numbering the signal blocks as described above has a numberof advantages. Numbering the signal blocks open the possibility toshuffle signal blocks in an order different from their original order,as long as the shuffling is done within a group of signal blocksidentified by unique signal block numbers. By detecting the signal blocknumbers upon reproduction, a deshuffling can be carded out on theshuffled signal blocks so as to obtain the original sequence order ofthe signal blocks.

Another measure that can be carried out is repeating a signal block, forthe reason that the recording and subsequent reproduction of theinformation included in the signal block require a higher protectionagainst transmission errors. Repeated signal blocks will have the samesignal block numbers so that they are identifiable upon reproduction.

Further, upon detection of the signal block numbers, it can be detectedwhether a signal block has been lost because of transmission errorsoccurring during the subsequent recording and reproduction step. Whenmissing a signal block number in a sequence of signal block numbers, itcan be decided that the signal block having the signal block number thathas been missed is lost. Upon such detection, an error correction orconcealment can be carried out so as to correct or conceal the missingsignal block.

Next, an explanation will be given of the functioning of the `trickplay` processing units 16 and 62 in the recording arrangement of FIG. 6and the reproducing arrangement of FIG. 7 respectively. For carrying outa trick mode (or feature mode) reproduction with the reproductionarrangement, the record carrier 40 is transported with a speed otherthan the nominal transport speed. FIG. 16 shows the record carrier 40having a number of slant tracks recorded on it. FIG. 16 also shows apath, denoted by the reference numeral 120, via which path the readinghead 52 scans the record carrier in said trick mode. Generally, theinformation in the tracks is recorded by at least two heads having gapsof different azimuth angles, so that even numbered tracks have the oneazimuth and odd numbered tracks have the other azimuth. That means that,when scanning the record carrier along the path 120, the head 52, whichhead has one of the two azimuth angles, will be able to read informationfrom only the even numbered or only the odd numbered tracks.

In order to enable a reproduction of video information during a trickplay mode, especially in the case of video information being recorded ina data reduced form, it is required to add special trick playinformation in special locations in the tracks such that those locationsare scanned by the head 52 for the various transport speeds for therecord carrier that are possible in a trick play mode. This trick playinformation is special video information recorded in addition to thenormal play video information that has been recorded in the tracks inthe way described above. As a consequence some of the signal blocks in atrack comprise this trick play information, which should be scanned andread by the head 52 in the trick play mode.

It should be noted here that the MPEG data, as far as the video data inthe MPEG datastream is concerned, comprises data reduced videoinformation. To realize such data reduced video information theinformation corresponding to one picture is intra encoded so as toobtain so called I-frames. A higher data reduction can be obtained bycarrying out an interframe encoding on at least two subsequent pictures,resulting in an I-frame for the first picture and a P-frame for thesecond picture. For recreating the two pictures an intraframe decoding,inverse to the intraframe encoding, must be carried out on the I-frameinformation, so as to regenerate the first picture, and an interframedecoding, inverse to the interframe encoding, must be carded out usingboth the I-frame information and the P-frame information, so as toregenerate the second picture.

In a trick mode, only I-frame information can be used to regenerate avideo signal, as retrieving not only the I-frame information but alsothe corresponding P-frame information so as to realize an interframedecoding, is not possible. Therefore, in order to obtain the `trickplay` information, only the information stored in I-frames included inthe serial MPEG datastream is extracted and used as `trick play` data.

It can be said that in a special location in a track, such as in thelocation indicated by the hatched area 122 in the track 124 in FIG. 16,a number of signal blocks are inserted that comprise the `trick play`information. FIG. 17 shows the sequence of signal blocks in the track124. The hatched area 122 in FIG. 16 is formed by the sequence of signalblocks SB_(i) to SB_(j) inclusive in the sequence given in FIG. 17. Thethird block sections TB in the signal blocks comprised in the trick playarea 122 of the track now comprise an indication that the signal blockscomprise trick mode information. This indication information is denotedby `T` in the third block sections TB3 of the signal blocks SB_(i) toSB_(j) inclusive. The signal blocks stored in the track prior to thetrick play area 122, as well as the signal blocks stored in the trackafter the trick play area 122 comprise information indicating that theinformation stored in the signal blocks is normal play information. Thisindication information is denoted by `N` in the third block sections TB3in the signal blocks SB_(i-2), SB_(i-1), SB_(j+1).

The `trick play` processing unit 16 of FIG. 6 is thus capable ofderiving the trick play information from the MPEG datastream applied toits input 17, storing the trick play information in those signal blocksthat are specifically meant for storing the trick play information in aspecific location in a track and for inserting the indicationinformation indicating that the signal block is a signal block in whichtrick mode information is stored in the third block sections of thosesignal blocks. The `normal play` processing unit 14 will further becapable of storing the indication information indicating that the signalblocks generated by the unit 14 comprise normal play information, in thethird block sections of those signal blocks.

When the reproducing arrangement is switched into its trick mode, the`trick play` processing unit 62 will be capable of detecting thosesignal blocks that have the `T` identification stored in their thirdblock sections and to retrieve the information from those signal blocksfor further processing so as to realize a reviewing option during thetrick mode.

REFERENCES

(1) European patent application no. 492,704 (PHN 13.546)

(2) European patent application no. 93.202.950 (PHN 14.241)

(3) European patent application no. 93.201.263 (PHN 14.449)

(4) Grand Alliance HDTV System Specification, Draft document, Feb. 22,1994.

(5) U.S. patent specification No. 5,142,421 (PHN 13.537)

We claim:
 1. Recording arrangement for recording an information signalin tracks on a record carrier, the recording arrangement comprisinganinput terminal for receiving the information signal, channel encodingmeans for channel encoding the information signal so as to obtain achannel signal suitable for recording in a track on said record carrier,writing means for writing the channel signal in the track, the channelsignal comprising sequential signal blocks, each signal block comprisinga first block section which comprises a synchronization signal and asecond block section which comprises a number of channel bytes,characterized in that the information signal is an MPEG informationsignal in accordance with an MPEG format, the MPEG information signalconsisting of a single sequential series of transport packets having asingle priority, that the channel encoding means are adapted to storeall information except sync bytes included in each one of a plurality ofgroups of x transport packets of the MPEG information signal in thesecond block sections of a corresponding distinct one of a plurality ofgroups of y signal blocks of the channel signal, that the second blocksection of at least the first signal block of each group of y signalblocks comprise a third block section for storing identificationinformation identifying the signal block as being the first signal blockof a group of y signal blocks, and that x and y are integers such thatx≧and y>1.
 2. Recording arrangement as claimed in claim 1, characterizedin that y>x.
 3. Record carrier obtained with the recording arrangementas claimed in claim
 1. 4. Record carrier as claimed in claim 3,characterized in that, sequence number information relating to thesequence number of the signal blocks is stored in the block sections ofthe signal blocks.
 5. Record carrier as claimed in claim 3,characterized in that the channel signal recorded in a track comprises afirst group of y first signal blocks so as to enable a normal play modeusing the video information stored in said first group of y first signalblocks during a normal play reproduction mode, and comprises a secondgroup of z second signal blocks in which a trick mode video signal isstored so as to enable a trick play mode using the video informationstored a said second group of z second signal blocks, that indicationinformation indicating whether a group comprises first signal blocks orsecond signal blocks is stored in the third block sections of at leastone signal block of the first and second group.
 6. Record carrier asclaimed in claim 3, characterized in that, the third block section ofthe second block sections of at least those signal blocks in a group ofy signal blocks that comprises the start portion of a transport packetcomprise information relating to a transport packet sequence numbercorresponding to the transport packet having its start portion stored inthe second block section of the signal block.
 7. Record carrier asclaimed in claim 3, characterized in that the third block section of thesecond block sections of at least those signal blocks in a group of ysignal blocks that comprises the start portion of a transport packetcomprise timing information for said transport packet having its startportion stored in the second block section of the signal block. 8.Reproducing arrangement for reproducing an information signal that hasbeen recorded in the form of a channel signal in tracks on a recordcarrier, the reproducing arrangement comprisingreading means for readingthe channel signal from a track,the channel signal comprising sequentialsignal blocks, each signal block comprising a first block section whichcomprises a synchronization signal and a second block section whichcomprises a number of channel bytes, channel decoding means for channeldecoding the channel signal so as to obtain the information signal, anoutput terminal for applying the information signal, characterized inthat the information signal recorded in the tracks is an MPEGinformation signal in accordance with an MPEG format, the MPEGinformation signal consisting of a single sequential series of transportpackets having a single priority, all information except sync bytes ineach one of a plurality of groups of x transport packets of the MPEGinformation signal being stored in the second block sections of acorresponding distinct one of a plurality of groups of y signal blocksof the channel signal, that x and y are integers such that x≧1 and y>1,that the second block section of at least the first signal block of eachgroup of y signal blocks comprise a third block section for storingidentification information identifying the signal block as being thefirst signal block of a group of y signal blocks, the reproducingarrangement further comprising first retrieving means for retrieving theinformation contained in the x transport packets of the MPEG informationsignal from the group of y signal blocks, second retrieving means forretrieving said identification information from the third block sectionsof the first signal blocks in each group of y signal blocks. 9.Reproducing arrangement as claimed in claim 8, characterized in thaty>x.